"Onegai! Einzbern Sōdanshitsu" is a short anime series set in the "Fate" universe, specifically focusing on the Einzbern family, a prominent magical lineage known for their alchemical prowess and involvement in the Holy Grail Wars. The narrative revolves around Irisviel von Einzbern, a homunculus created by the Einzbern family, and her interactions with her maidservant, Sella, and her combat instructor, Leysritt. The series adopts a comedic and slice-of-life approach, contrasting with the darker and more action-oriented tone of the main "Fate" series.

The story unfolds in the Einzbern Castle, where Irisviel, Sella, and Leysritt engage in various daily activities and humorous misadventures. Irisviel, despite her regal appearance and role as a homunculus, exhibits a playful and curious personality, often leading to comedic situations. Sella, the diligent and strict maidservant, frequently finds herself exasperated by Irisviel's antics, while Leysritt, the more laid-back and physically imposing combat instructor, provides a contrasting dynamic with her calm demeanor and occasional clumsiness.

The episodic nature of the series allows for self-contained stories that explore the characters' personalities and relationships. Themes of family, duty, and the contrast between the Einzbern's aloof reputation and the warmth of their daily lives are subtly woven into the narrative. The series also includes references to the broader "Fate" lore, such as the Holy Grail War and the Einzbern family's history, providing additional context for fans familiar with the franchise.

While the series primarily focuses on humor and lighthearted moments, it occasionally touches on the underlying tragedy of the Einzbern family's existence, particularly Irisviel's role as a homunculus created for a specific purpose. These moments add depth to the characters and their interactions, offering a nuanced portrayal of their lives within the confines of the Einzbern Castle. Overall, "Onegai! Einzbern Sōdanshitsu" serves as a charming and accessible entry point into the "Fate" universe, emphasizing character-driven storytelling and comedic elements.